Assessment of the impacts of mobile bottom-contacting fishing gears on epibenthic communities of the Scotian Shelf and Gulf of Maine (Atlantic Canada)

An assessment of the impacts of mobile bottom-contacting gears (MBCG) on eight previously identified epibenthic communities off Nova Scotia, Canada, is presented using risk-based indicators of Relative Benthic Status (RBS). Indices of both existing biomass relative to carrying capacity of the whole epibenthic community (RBS_tot), and that of the 10% most sensitive fauna (RBS_sen), were quantified and mapped. Substantial regional and habitat-related differences in RBS were identified. Most of the eastern Scotian Shelf, where five benthic community types are recognized, showed low fishing intensity and high seabed status. In contrast, a community characterized by long-lived individuals of echinoderms, sponges and cnidarians on eastern Georges Bank and in the Inner Bay of Fundy, was severely impacted. RBS_tot for that community was in good status on only 48% of the area of the habitat, while RBS_sen met that threshold on only 35% of the area. Our approach allows for the large-scale evaluation of the impacts of MBCG on the benthic communities as a whole and enables evaluation of management scenarios aimed at reducing its environmental effects.